The vascularization (angiogenesis) of tumors plays an important role in the growth and hematogenous dissemination of neoplasms, and the inhibition of angiogenesis is being increasingly appreciated as a novel and effective therapeutic strategy for limiting tumor growth and spread. Endothelial growth factors play a dominant role in angiogenesis, many of which are dependent on the presence of heparan for binding to their cognate cell-surface receptors and subsequent initiation of downstream signaling cascades that lead to endothelial cell proliferation. We hypothesize that the sequestration of heparan would prevent the binding of heparan-dependent growth factors to endothelial cells and inhibit their mitogenic effects. Based on existing knowledge on the structural requisites for the molecular recognition of heparan sulfate, we have constructed a preliminary pharmacophore for heparan sulfate binding, and propose to screen a carefully chosen focused library of compounds. We will first test the hypothesis that small molecules possessing the pharmacophore will bind heparan sulfate, using heparin as a model heparin compound. We will then examine if the binding will be manifested in inhibition of endothelial growth factor activity using a small subset of compounds. The utilization of a novel dye-displacement spectrophotometric assay as the primary high-throughput screen has already yielded provisional "hits", one of which has been shown to inhibit both FGF and VEGF-induced angiogenic activity in human umbilical endothelial cells. Promising compounds will be examined in greater detail with respect to details of the physical interactions with heparin. Further biological activity will be ascertained in chicken chorioallantoic membrane assays. [unreadable] [unreadable]